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PMP Quality Tools: Pareto Chart, Fishbone Diagram, Control Chart
Pareto shows the few causes behind most defects; fishbone explores possible causes; a control chart shows whether a process is stable.
In simple words
Each quality tool answers one question. Which problems happen most often? Pareto chart. What could be causing this? Fishbone diagram. Is the process stable? Control chart.
What the PMP exam wants
Pareto chart: bars sorted from most to least frequent. The 80/20 idea says a few causes produce most problems, so fix those first. Fishbone (Ishikawa, cause-and-effect): lists possible root causes by category, such as people, method, machine, material, measurement, environment. Control chart: plots a process over time against control limits.
Control limits (usually ±3 sigma) come from the process data and show whether it is stable. Specification limits come from the customer or requirements and show what is acceptable. A process can be stable but still make out-of-spec parts. Other tools to recognize: histogram, scatter diagram (correlation), checklist, flowchart.
Real example
Of 200 FAT stoppages, gripper misses and vision false rejects cause 75%. A Pareto chart shows this, so the team fixes those two first. A fishbone session then explores why the gripper misses: part variation, air pressure, program offsets.
The common trap
Control limits ≠ specification limits. Control limits are the voice of the process; spec limits are the voice of the customer.
Remember: Pareto = prioritize. Fishbone = find causes. Control chart = stable or not.
🗝 Words to notice in the question
“limited capacity” + many defect categories → Pareto. “root cause” → fishbone. “stable?” → control chart
Try 2 practice questions
Choose an answer, or open “Show the answer.”
Question 1 The team wants to decide which defect types to fix first, based on how often they occur. Which tool fits best?
Show the answer
Answer: B. Pareto ranks causes by frequency.
Question 2 Where do specification limits and control limits come from?
Show the answer
Answer: B. Spec = customer's voice. Control = process's voice.
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